AEROACOUSTIC DESIGN AND BROADBAND NOISE PREDICTIONS OF A TURBOFAN STAGE WITH SERRATED OUTLET GUIDE VANES

摘要

This work, realized in the framework of the European project TurboNoiseBB, presents the aeroacoustic design of serrated OGVs (Outlet Guide Vanes), including details on their broadband noise and aerodynamic performance. The serrated OGV corresponds to a modified stator from a turbofan model tested at the AneCom facility (Germany) and shared by the Consortium. Leading edge sinusoidal patterns with varying amplitude and wavelength along the span are designed in collaboration with Safran Aircraft Engines. Serrations are adjusted to account for the turbulence characteristics provided by RANS calculations. Optimal parameters are found using simple design rules discussed in the paper. Down selection of serrated OGV designs (patent pending) was performed in accordance with industrial specifications. Broadband noise simulations are performed using a CAA code solving the linearized Euler equations with a synthetic turbulence model. Numerical predictions at approach conditions are compared to available experimental measurements and an analytical Amiet-based model. Predictions on the untreated case show a fairly good agreement by comparison to the PSD measured at the bypass casing, and a PWL reduction around 3-4 dB roughly estimated by the design process is numerically achieved by the present method.